We have an OData connection. (Version 3 and 4) In the Teiid documentation it states that only some of the OData v3 connections currently work. Unfortunately our OData v3 does not work. We are getting the following error:

This is more of a server issue, than Designer. Teiid 8.9 will introduce OData 4 production support, but unfortunately the translator will still be at v2. There should be updated support in Teiid 8.10. Given that Odata4j (the library that Teiid is using for OData consumption) has a hard-coded limitation here this would probably be difficult for us to workaround.

To be more specific tech preview of OData 4 support is coming in Teiid 8.9 based on Apache Olingo project. This is currently only on the producing Teiid data as OData service. As per consuming OData 4 as source will hopefully make it into Teiid 8.10. Also there will NOT be support for OData 3, we are skipping that support altogether.

That is debatable argument. But I have not seen any strong indication that Olingo project made any strong efforts to support it. Granted it is consumption side, Teiid still need to understand the $metadata and request ad response formats which would be time consuming to implement given the general lack of interest on this version of the spec. I believe only M$ specific services are designed so far on this version, so we would be alienating few users, but general consensuses in seems to be V2 and V4 are the stable versions.